How do I remove downtime completely?

My mom’s ex put a downtime on my tablet a few years ago and she doesn’t have the password to turn it off. I’ve tried changing my icloud password already and using “Forgot Password” but to no avail. Now, the entire “Forgot Password” option isn’t even available. I can’t even sign out of my account on my tablet to reset it. If anyone can help it’d be incredibly appreciated.